Why did the airline give you the big brushoff? It may well have something to do with your nonverbal communication skills or, more specifically, your lack of them.

So says Mark Bowden, a Toronto-based body language expert and the author of the book Winning Body Language .

But if you dig deep and release your inner caveman (or cavewoman), you'll find yourself seated comfortably in first-class on that flight, and at a good price, Bowden says. It's all about tapping into the true language of airline travel upgrades , and it turns out that includes nonverbal skills used by cave dwellers thousands of years ago.

Prehistoric humans didn't use verbal language to signal they wanted a fire lit or a mastodon taken down for the big feast Friday night. "Basic body language" got those tasks done, and the same holds true today for airline consumers looking to advance their traveling status.

In general, Bowden says, the sunnier the nonverbal disposition, the better.

"It's generally shown across the planet that open body language and a smile will create an unconscious reaction in the recipient to want to give back to you -- be it an upgrade, a better seat or a free drink," he says.

Bowden advises using the following caveman-like nonverbal gestures (he calls them "Neanderthal nuances") to land that cushy seat in first class time and time again:

Be a prehistoric pal. Show your sunny side when approaching a decision-maker who can expedite your first-class seat. "That comes in handy when meeting upgrade gatekeepers," Bowden says. "By opening your arms in a welcoming way, you show others you mean no harm. A smile is a great addition."

Show your minimalist side. This one requires you to verbalize a request, but with a twist. When you sidle up to an airline attendant and ask, "Hey, do I see an empty seat in first class?" raise your eyebrow ever-so-gently when you do so. "Sometimes less is more," Bowden says. "By slightly raising your eyebrows you will be perceived as an approachable person." And it's approachable people who win first-class seats.

Try an eye crinkle. It's no use trying to get away with a fake smile -- the airline attendant will know it. But if you smile while showing the wrinkles around eyes, you'll appear more genuine and hike your odds of getting into first class .

Whatever you do, don't show any signs of anger, verbal or nonverbal. Even so-called "polite pleading" will turn a flight attendant off; they're used to being treated rudely by travelers, but that doesn't mean they like it.